1. Field of the Invention
The present invention relates to a telephone system and in particular to a key telephone system.
2. Background of the Related Art
In general, a key telephone system is a small telephone exchange system for relaying telephone communication between extensions or between an extension and an outside phone by connecting plural telephones with extension numbers in order to use limited telephone lines by a great number of people. The key telephone system consists of a main device, telephone sets, lines connecting the main device with the telephone sets and an additional unit for operating the system more efficiently.
However, in the related unit key telephone system, the system can be limited to a maximum number of voice time slots provided through one switching unit, and it is not possible to expand voice channels to exceed the limited maximum number. In addition, in the related art key telephone system, a request for capacity expansion of the system cannot be satisfied.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.